We have found that mitosis in the germinative zone of the frog lens depends upon pituitary hormones. Wound hyperplasia also requires the presence of such materials. During the coming year we will attempt to purify these substances from frog pituitaries. Heretofore our studies have been performed with crude extracts or mammalian hormones. After purification is accomplished, we hope to define precisely the material(s) which governs growth in the lens. Moreover work on control of corneal epithelial and endothelial repair is being started. We have been able to isolate histone and nonhistone chromosomal proteins from lenticular tissue and will proceed to define their role(s) in cell cycle control of the tissues mentioned above.